FAA Chart = Not For Navigation?

[HighFlyingA380]

Why does my FAA chart (in particular the St. Louis VFR flyway TAC) say "NOT TO BE USED FOR NAVIGATION"??? I understand it obviously doesn't contain all pertinent info, such as the other side or a sectional, but it obviously has it's specialized uses. I just don't get it...

 

[flyingron]

That's so you use the scale on your plotter marked "Not for plotting."

 

[midlifeflyer]

I think it's just that as merely a "guide for visual orientation... designed for use in conjunction with TACs" that depict "recommended" flight paths and altitudes (FAA product description) they are not subjected to the same rigorous review for obstacles, etc as the associated chart and are not designed for primary navigation reference.

 

[LDJones]

I think another reason is they are not updated on the same cycle as the regular navigational charts, hence the lack of assurance of current nav/obstacle data.